1. Field of the Invention
The invention relates to a smoke evacuator used for a surgical laser or cautery plume. More particularly, the invention relates to a smoke evacuator having an increased number of interactive controls enabling the evacuator to adjust operating conditions based on sensed backpressure and to immediately reduce vacuum pressure by activating a solenoid relief valve when the evacuator senses tissue invagination.
2. Description of the Prior Art
Laser surgery and cauterization are widely used and accepted medical procedures. During these procedures, the energy of the laser vaporizes tissue onto which the beam is directed. The vaporized tissue becomes what is referred to as "smoke". This smoke must be removed from the surgical area because of sanitary concerns affecting the patient and the medical staff. The smoke must also be removed so that the medical staff has a clear view of the surgical area. The medical staff generally removes the smoke from the surgical area by using a suction device, a small vacuum pump, known as a smoke evacuator.
Most present-day smoke evacuators include several lengths of hose, a nozzle at the surgery end of a hose, a motor or pump that produces suction through the nozzle and hoses, a plurality of filters for removing particulates and potentially harmful materials from the smoke flowing through the tubes, and a manual control for adjusting the suction force produced by the motor or pump.
In operation, a user maneuvers the nozzle around the surgical site, directing the nozzle toward the area of smoke, while controlling the suction power of the motor or pump. Occasionally, the evacuator nozzle becomes obstructed by a surgical object or tissue. This is commonly referred to as tissue invagination.
When the evacuator nozzle becomes obstructed, the user typically has two options. First, the user may pull the nozzle away from the tissue. However, when the user does this, the user runs the risk of damaging the tissue. Alternately, the user may manually reduce the suction of the evacuator or wait for the evacuator to sense the invagination and automatically reduce the suction. Once the suction is reduced, the tissue is released from the nozzle. However, the suction is not immediately reduced to zero, and the tissue may be damaged while the suction gradually decreases.
Another problem experienced by present-day smoke evacuators occurs when one or more of the filters becomes obstructed by liquid and solid particulate matter removed from the surgical site. When a filter becomes partially or fully obstructed, the suction capability of the evacuator is reduced. Therefore, the evacuator is not performing as well as possible, and the suction should be increased to compensate for the loss of performance of the filter. The user must, however, be notified of the loss of suction due to an obstructed filter if the user is to manually increase the suction provided by the evacuator or replace the filters to remove the obstruction. Similarly, the evacuator must be notified of the loss of pressure if the suction is to be increased automatically.
The suction pressure should continuously be monitored to ensure that the operator is properly and accurately informed when an obstruction is detected. Many evacuators monitor the suction, but only provide notice to the operator when the filter is completely obstructed and must be replaced. Other evacuators monitor the suction, and increase or decrease the motor or pump speed in discrete steps as required to keep the suction at a constant level. However, these evacuators do not vary the motor or pump speed while considering other variables, such as the diameter of the suction hose being used with the evacuator. Consequently, the variation in motor or pump speed is not always accurate enough to hold the suction pressure at a constant level.
Considering the state of the prior art, a need exists for a laser smoke evacuator capable of continuously monitoring the differential pressure across a filter, while considering variables of equipment being used with the evacuator, such that the motor or pump speed may be automatically adjusted to maintain a constant suction pressure at the nozzle. Additionally, a need exists for an evacuator providing a continuous display of the state of the filter, such that one using the evacuator has sufficient notice when the filter must be replaced. Finally, a need exists for a laser smoke evacuator capable of sensing tissue invagination and reacting immediately to release the tissue by activating a relief valve to release suction at the nozzle and by transmitting a signal to turn off the motor or pump until the tissue has been released. The present invention provides such an evacuator.